Canadian Plant Disease Survey 2019 Volume 99: Disease Highlights 2018

Abstract

The British Columbia Ministry of Agriculture (BCAGRI) Plant Health Laboratory provides diagnoses of diseases caused by fungi, bacteria, viruses, plant parasitic nematodes and insect pests of agricultural crops grown in British Columbia. Between January 1 and November 30, 2018, the laboratory received 921 samples including Christmas trees, field crops, greenhouse vegetable and floriculture crops, forest nursery seedlings, herbaceous and woody ornamentals, small fruits, tree fruits, nuts and specialty crops for diagnosis. No significantly new or unusually high level of any disease was detected in the samples. METHODS:The BCAGRI Plant Health Laboratory provides diagnoses for diseases caused by fungi, bacteria, viruses, plant parasitic nematodes, and insect pests of agricultural crops grown in British Columbia. Samples were submitted to the laboratory by ministry staff, growers, agri-businesses, munici-palities and Master Gardeners. Diagnoses were accomplished by visual and microscopic examination, culturing onto artificial media, biochemical identification of bacteria using BIOLOG®, serological testing of viruses, fungi and bacteria with micro-well and membrane-based enzymelinked immunosorbent assay (ELISA). Molecular tech-niques (polymerase chain reaction (PCR) (conventional and/or real time) were used for some species-specific diagnoses. Electron microscopic examination was performed on samples with unknown virus-like symptoms. Some specimens were referred to other laboratories for identification or confirmation of the diagnosis. RESULTS AND COMMENTS: Overall in 2018, British Columbia had a wet spring followed by a long dry summer. The wet weather in the spring supported bacterial blights on woody ornamentals, tree fruits and berry crops. Fire blight incidence was higher in tree fruit and woody ornamental crops. Fruit rots and postharvest rots were much lower than normal due to dry weather in late summer. Diseases and their causal agents diagnosed on crop samples submitted to the laboratory are presented in the following Tables 1-11 organized by crop category. Diagnoses not listed include: abiotic symptoms such as nutritional stress, pH imbalance, water stress, drought stress, physiological response to adverse growing conditions, genetic abnormalities, environmental and chemical stresses including herbicide damage, fruit abortion due to lack of pollination, insect-related injury and damage where no conclusive causal factor was identified.

Canadian Plant Disease Survey 2020 Volume 100: Disease Highlights 2019

“…In upper leaf canopies, disease severity was trace to slight in 92.1% of the fields, moderate in 1% and severe in 6.9% of the fields. Disease levels in 2019 were similar to that found in 2018 but lower than previous years Banik et al 2014Banik et al , 2019Wang et al 2015), which was mostly due to dry weather conditions during the growing season, which were not very favourable for the development leaf spot diseases. Cochliobolus sativus (causal agent of spot blotch) and Pyrenophora teres (net blotch) were the principal pathogens isolated from infected leaf tissues and caused the most damage in the fields surveyed.…”

“…Pyrenophora avenae, causal agent of pyrenophora leaf blotch, was the most prevalent leaf pathogen in oat (Table 2). This pathogen was isolated from 25% of fields, which was lower than levels reported in the last few years Banik et al 2017Banik et al , 2019. Cochliobolus sativus and S. avenae were isolated from 13.2% and 3.5% of commercial fields, respectively (Table 2).…”

“…All foliar diseases were observed at a much higher incidence and severity than in 2018, likely due to frequent rain showers in the summer of 2019 (Chang et al 2019). No stripe rust (Puccinia striiformis f. sp.…”

Plasmodiophora brassicae Inoculum Density and Spatial Patterns at the Field Level and Relation to Soil Characteristics

“…Previously proposed soil sampling strategies for the detection of P. brassicae suggest the gathering of soil samples along a diagonal [14], or the collection of 40 subsamples in a 'W' transect that should be pooled in a composite sample and complemented with samples from high moisture areas, headlands and the field entrance [48]. Clubroot symptom-based sampling strategies propose evaluation for the presence of galled roots in at least 50 plants collected from a 20-30 m 2 area near the field entrance; if symptoms are observed, further sampling is conducted along the field following a 'W' transect, whilst if no symptomatic plants are found, no further sampling is conducted [72]. Although previous sampling strategies may be appropriate in many cases, based on the spatial patterns observed in this study sampling should be more intense at the field edges, converging at the field entrance.…”

A case of multifocal cutaneous alternariosis in a patient with hairy cell leukemia

“…They are ubiquitous within the environment, commonly found as saprophytes in soil, and have a worldwide geographic distribution. Alternaria spp are common plant pathogens in Saskatchewan and across Canada, found in crops and cultivated and wild vegetation (3).…”